Conventionally, in a multicarrier communication system, a technique has been used where a multicarrier communication apparatus on a receiving side combines a last received packet and re-received packet and performs decoding, thereby obtaining the diversity gain in the time domain and reducing a bit error rate of the packet.
Further, another technique has been developed where a multicarrier communication apparatus on a transmitting side modulates a packet using a different constellation pattern from that of the last transmitted packet when re-transmitting the packet, and exchanges higher-order bits and lower-order bits of the last transmitted packet to obtain the diversity gain in the time domain, thereby reducing a bit error rate of the packet (for example, see Patent Document 1).    Patent Document 1: Japanese Patent Application Laid-Open No. 2003-309535